1. Field of the Invention
The present invention relates generally to man-machine interfaces and more particularly to such an interface for measuring the mobility of human joints.
2. Description of the Background of the Invention
Devices and systems have been proposed to measure relative joint motion between two jointed skeletal segments. A number of systems are presently commercially available. Those systems are typically either glove-based systems of the type disclosed in U S. Pat. No. 4,414,537 to Grimes or exoskeletal systems of the type disclosed in U.S. Pat. No. 4,986,280 to Marcus, et al. Each of those systems has its limitations.
In the patent to Grimes, groups of sensors are fixed to the back of a glove which sensors are responsive to the flexing of various joints. Because the sensors are rigidly fixed to the glove, they are precisely located, but they are also subject to tensile forces whenever the joint is flexed. The tensile force added as a result of the flexing of the joint introduces an error into the signal produced by the sensor. Thus, the sensor does not provide an accurate signal representative of the degree of flex of the joint.
The device disclosed in Marcus, et al. is an exoskeletal device which is cumbersome to work with. Although that device does not suffer from the inaccuracies created by tensile forces acting on the sensors, the device of Marcus, et al. must be precisely positioned and rigidly strapped to the patient such that in certain cases involving injury or trauma, a device of that type simply cannot be used.
Accordingly, it is a general object of the present invention to provide an improved system for measuring human angular joint, limb, and body motion which substantially reduces or overcomes the foregoing problems. A more specific object of the invention is to provide the medical and scientific communities with a human body motion analysis input system that has the accuracy and data production speed useful for their needs and which has a man-machine interface that is accurate, easy to set up, calibrate, and use.